The invention relates generally to a pressurized chemical dispensing apparatus, and more particularly to a hand-held apparatus particularly suitable for use in dispensing two-component systems, more particularly urethane foams, wherein the apparatus includes a dispensing assembly interconnected to the canister supplies. Optionally the apparatus is contained within a kit which permits one-handed operation.
The use of urethane and similar expandable foams has increased over the years for numerous applications. Urethane foams are well known as having desirable characteristics useful for many applications, such as insulation, adhesives or sealants. Urethane foams are also well known for their compatibility with low cost blowing agents which allow such foams to be applied by way of pressurized containers as well as their natural adhesive qualities which allow such foams to bond excellently to any number of substrates. Typically, urethane foams are the reaction product of two individual components, one being an isocyanate and the other being a resin. These two individual components when reacted together under pressure, give the resultant foam various chemical compositions, each such composition having significant utility in a particular application. Thus, urethane foams may be specially formulated to provide a final foam which is rigid, semi-rigid or flexible.
Closed cell urethane foams have particular utility in building and structural insulation while open cell urethane foams have particular utility in packaging or non-insulating purposes. Regardless of cell structure, two-component urethane foams are typically formed by mixing the two or more individual foam components together when the foam components exit respective supply containers. Individual material supply tubes leading from each foam component container convey the foam components to a foam dispensing apparatus, such as a nozzle.
There are numerous applications in which polyurethane foam is used at a site for any number of applications in addition to its traditional use in the building trades as a source of insulation. Recently polyurethane foam has become used with increasing frequency as a sealant in the building trades for sealing spaces between window and door frames and the like and as an adhesive for glueing flooring and roof tiles and the like. The polyurethane foam for such in-situ applications is typically supplied as a one-component froth foam or a two-component froth foam. A one-component foam means that both the resin and isocyanate for the foam is supplied in a single pressurized container and dispensed from the container through a valve or gun attached to the container. A two-component “froth” foam means that one component is supplied in one pressurized container, typically the “A” container (i.e., polymeric isocyanate, fluorocarbons etc) while the resin is supplied in a second pressurized container, typically the “B” container (i.e., polyols, catalyst, flame retardants etc.). Typically, two-component kits use pressurized cylinders which are connected by hoses to a dispensing gun. There are advantages and disadvantages to one-component and two-component foams. One of the advantages of the two-component system is its relatively long shelf life resulting from the fact that the chemicals are not mixed until they encounter one-another in the dispensing gun.
One application for a hand-held, portable two-component polyurethane froth foam kit exists in the mining industry. In the event of a fire in a shaft being tunneled, standard procedure is to extinguish the fire by sealing the shaft with a fire “door” and then pumping out from the shaft sealed by the door, the air in the shaft to extinguish the fire. It has been found that polyurethane foam is excellent for sealing the bulkhead or door to the tunnel. As already noted, the polyurethane foam has an adhesive characteristic and the foam can be formulated to provide a relatively quick tack free time with little permeability for gas escape. Surprisingly, the fire door is not adjacent an open flame, and whatever temperature the gases exhausted from the shaft are, they are not sufficiently high in temperature to disintegrate the foam. Because of its long shelf life, a two-component foam is ideal for this application. Standard procedure is to simply provide two-component kits at the shaft being tunneled to seal and secure the fire door or bulkhead to the shaft in the event of a fire.
Different packaging arrangements are used by different manufacturers. Many two-component kit packages use some form of tray with knock-out holes through which the hoses extend after the box is opened and the hoses attached to the cylinder's valved fitting. However, there is at least one two-component polyurethane froth foam box which utilizes cylinders equipped with “dip tubes” which extend through the outlet valve from the inside bottom of the cylinder. This allows the cylinders to be placed upright in the box instead of upside down. This carton does not use a tray and has the hoses extend out the side of the box through knock-out plugs. The carton is carried by a strap affixed to the top cover. The top cover is a flap which has to be opened and closed to gain access to the cylinder's valve after the hoses are connected to the cylinders.
What has been missing from the Prior Art however, is a foam dispensing device which couples both fail-safe operation by a two-stage activation procedure, coupled with a dispensing mechanism whereby the dispensing means: is biased into a closed position; is actuated by rotational movement about a canister longitudinal axis; has an extendable nozzle extension; and has a means for preventing hose deformation/crimping during shipment.